The present invention relates to nuclear magnetic resonance (NMR) imaging and, more particularly, to a novel detector for determining when a portion-being-imaged is in motion, during a high-resolution NMR imaging procedure.
It is known that high-contrast magnetic resonance imaging of a portion of human anatomy, such as the eye, is possible. However, diagnosis of eye diseases by use of NMR imaging has been prevented due to certain technical limitations, so that radiologists frequently continue to use computed tomography examinations for eye studies in cases where magnetic resonance imaging (MRI) may potentially provide a higher contrast and more detailed image. In addition to the higher image quality potentially offered by MRI examinations, it is known that the x-ray dose attendant to computerized-tomography scanning is sufficiently large so that, in some cases, follow-up studies on any given patient are precluded. Conversely, MRI studies appear to be repeatable as often as necessary for a given patient. As described and claimed in our co-pending application Ser. No. 07/452,176, filed Dec. 18, 1989, assigned to the assignee of the present application and incorporated herein in its entirety by reference, we have developed specialized antennae to overcome some of the technical limitations for NMR imaging of the human eye and provide sensitivity and signal-to-noise ratio (SNR) characteristics which permit rapid high-resolution imaging of small structures (such as the lens, and the like) within the eye. While these receiver coils avoid the hitherto-encountered difficulties in awkwardness in placement of such reception coils in position and in maintenance in the placed position, even while being more easily tolerated by the patient during the MRI scanning process, some means must be provided to prevent data acquired when the anatomical portion has moved (such as when the patient's eye blinks or moves) from being included in the data set, as such inclusion will result in loss of resolution or other image imperfections, known as artifacts. Accordingly, a motion detector for determining when acquired data is not acceptable, is highly desirable.